Which two systems play a role in the fight or flight response?

The two systems are the autonomic nervous system [ANS] and the sympathetic nervous system [SNS].

Explanation:

When we encounter an acute stressor, our hypothalamus activates the autonomic nervous system [ANS], which will, in its turn, activate the sympathetic nervous system [SNS]. The adrenal medulla, activated by the ANS, releases the stress hormones adrenaline and noradrenaline. They increase arousal by activating the sympathetic nervous system. Then our heart beats faster and blood pressure increases. We breathe faster since, because our blood is being pumped rapidly, we need more oxygen. Finally, adrenaline releases glucose and fats into bloodstream, providing energy to parts of the body associated with the fight-or-flight response.